Talking about Angry Birds game, Actionscript 3, Box2D, Flash and Game development.
Here we go with another Angry Birds tutorial. Once you know how to kill the pigs, it’s time to make the camera follow the bird, so we can design levels wider than the stage.
The concept behind this feature is explained in the post following a body with the camera in Box2D – The smart way. I also applied the theory explained there to the bird.
Also, I skinned the crates with a new sprite called Rock, that I remove each time a crate is broken.
There’s nothing much to say, that’s what you’ll get:
and this is the script:
package {
import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;
import Box2D.Dynamics.*;
import Box2D.Collision.*;
import Box2D.Collision.Shapes.*;
import Box2D.Common.Math.*;
import Box2D.Dynamics.Joints.*;
public class Main extends Sprite {
private var world:b2World=new b2World(new b2Vec2(0,10),true);
private var worldScale:int=30;
private var bird:birdMc=new birdMc();
private var rock:Rock;
private var birdSphere:b2Body;
private var customContact=new customContactListener();
private var following:Boolean=false;
public function Main() {
world.SetContactListener(customContact);
var bg:backgroundMc=new backgroundMc();
addChild(bg);
addChild(bird);
debugDraw();
bird.x=170;
bird.y=270;
bird.buttonMode=true;
addWall(640,10,640,395);
addWall(640,10,640,-5);
addWall(10,240,-5,240);
addWall(10,240,1275,240);
for (var i:int=0; i<=4; i++) {
addBlock(20,20,1050,365-i*40);
addBlock(20,20,1150,365-i*40);
}
addBlock(80,20,1100,165);
addPig(20,1100,125);
addEventListener(Event.ENTER_FRAME,updateWorld);
bird.addEventListener(MouseEvent.MOUSE_DOWN,birdClicked);
}
private function addWall(w,h,px,py):void {
var floorShape:b2PolygonShape = new b2PolygonShape();
floorShape.SetAsBox(w/worldScale,h/worldScale);
var floorFixture:b2FixtureDef = new b2FixtureDef();
floorFixture.density=0;
floorFixture.friction=10;
floorFixture.restitution=0.5;
floorFixture.shape=floorShape;
var floorBodyDef:b2BodyDef = new b2BodyDef();
floorBodyDef.position.Set(px/worldScale,py/worldScale);
floorBodyDef.userData={assetName:"wall",assetSprite:null,remove:false};
var floor:b2Body=world.CreateBody(floorBodyDef);
floor.CreateFixture(floorFixture);
}
private function addPig(r,px,py):void {
var pigShape:b2CircleShape=new b2CircleShape(r/worldScale);
var pigFixture:b2FixtureDef = new b2FixtureDef();
pigFixture.density=1;
pigFixture.friction=3;
pigFixture.restitution=0.1;
pigFixture.shape=pigShape;
var pigBodyDef:b2BodyDef = new b2BodyDef();
pigBodyDef.position.Set(px/worldScale,py/worldScale);
pigBodyDef.type=b2Body.b2_dynamicBody;
pigBodyDef.userData={assetName:"pig",assetSprite:null,remove:false};
var pigSphere:b2Body=world.CreateBody(pigBodyDef);
pigSphere.CreateFixture(pigFixture);
}
private function addBlock(w,h,px,py):void {
var blockShape:b2PolygonShape = new b2PolygonShape();
blockShape.SetAsBox(w/worldScale,h/worldScale);
var blockFixture:b2FixtureDef = new b2FixtureDef();
blockFixture.density=0.5;
blockFixture.friction=10;
blockFixture.restitution=0.1;
blockFixture.shape=blockShape;
var blockBodyDef:b2BodyDef = new b2BodyDef();
blockBodyDef.position.Set(px/worldScale,py/worldScale);
rock=new Rock();
rock.width=w*2;
rock.height=h*2;
addChild(rock);
blockBodyDef.userData={assetName:"block",assetSprite:rock,remove:false};
blockBodyDef.type=b2Body.b2_dynamicBody;
var block:b2Body=world.CreateBody(blockBodyDef);
block.CreateFixture(blockFixture);
}
private function birdClicked(e:MouseEvent):void {
addEventListener(MouseEvent.MOUSE_MOVE,birdMoved);
addEventListener(MouseEvent.MOUSE_UP,birdReleased);
bird.removeEventListener(MouseEvent.MOUSE_DOWN,birdClicked);
}
private function debugDraw():void {
var worldDebugDraw:b2DebugDraw=new b2DebugDraw();
var debugSprite:Sprite = new Sprite();
addChild(debugSprite);
worldDebugDraw.SetSprite(debugSprite);
worldDebugDraw.SetDrawScale(worldScale);
worldDebugDraw.SetFlags(b2DebugDraw.e_shapeBit|b2DebugDraw.e_jointBit);
worldDebugDraw.SetFillAlpha(0.8);
world.SetDebugDraw(worldDebugDraw);
}
private function birdMoved(e:MouseEvent):void {
bird.x=mouseX;
bird.y=mouseY;
var distanceX:Number=bird.x-170;
var distanceY:Number=bird.y-270;
if (distanceX*distanceX+distanceY*distanceY>10000) {
var birdAngle:Number=Math.atan2(distanceY,distanceX);
bird.x=170+100*Math.cos(birdAngle);
bird.y=270+100*Math.sin(birdAngle);
}
}
private function birdReleased(e:MouseEvent):void {
following=true;
bird.buttonMode=false;
removeEventListener(MouseEvent.MOUSE_MOVE,birdMoved);
removeEventListener(MouseEvent.MOUSE_UP,birdReleased);
var sphereShape:b2CircleShape=new b2CircleShape(15/worldScale);
var sphereFixture:b2FixtureDef = new b2FixtureDef();
sphereFixture.density=1;
sphereFixture.friction=3;
sphereFixture.restitution=0.1;
sphereFixture.shape=sphereShape;
var sphereBodyDef:b2BodyDef = new b2BodyDef();
sphereBodyDef.type=b2Body.b2_dynamicBody;
sphereBodyDef.userData={assetName:"bird",assetSprite:bird,remove:false};
sphereBodyDef.position.Set(bird.x/worldScale,bird.y/worldScale);
birdSphere=world.CreateBody(sphereBodyDef);
birdSphere.CreateFixture(sphereFixture);
var distanceX:Number=bird.x-170;
var distanceY:Number=bird.y-270;
var distance:Number=Math.sqrt(distanceX*distanceX+distanceY*distanceY);
var birdAngle:Number=Math.atan2(distanceY,distanceX);
birdSphere.SetLinearVelocity(new b2Vec2(-distance*Math.cos(birdAngle)/4,-distance*Math.sin(birdAngle)/4));
}
private function updateWorld(e:Event):void {
world.Step(1/30,10,10);
for (var currentBody:b2Body=world.GetBodyList(); currentBody; currentBody=currentBody.GetNext()) {
if (currentBody.GetUserData()) {
if (currentBody.GetUserData().assetSprite!=null) {
currentBody.GetUserData().assetSprite.x=currentBody.GetPosition().x*worldScale;
currentBody.GetUserData().assetSprite.y=currentBody.GetPosition().y*worldScale;
currentBody.GetUserData().assetSprite.rotation=currentBody.GetAngle()*(180/Math.PI);
}
if (currentBody.GetUserData().remove) {
if (currentBody.GetUserData().assetSprite!=null) {
removeChild(currentBody.GetUserData().assetSprite);
}
world.DestroyBody(currentBody);
}
}
}
if (following) {
var posX:Number=bird.x;
posX=stage.stageWidth/2-posX;
if (posX>0) {
posX=0;
}
if (posX<-640) {
posX=-640;
}
x=posX;
}
world.ClearForces();
world.DrawDebugData();
}
}
}
We are only one step away from creating a playable Angry Birds level, then I'll explain everything line by line.
Meanwhile, download the source code.
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